2.5" collector mod - edelbrock header [Archive]

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turboedpickup

10-09-2006, 10:53 AM

found this on H-T, halfway in the thread - some guy has pictures of how he modded the collector to 2.5"

http://www.honda-tech.com/zerothread?id=1226335

rushi

10-09-2006, 01:35 PM

You really think to get some gains with this to D? 4-2-1's are not ment for high/maximum power anyway.

I did similar mod to my BMW (had Schrick 292 cam, 40mm Dellorto dual side-drafts etc, ~150hp).
All I got was lost bottom-end torque, and that was with 1.8 engine.

2.5" is good with merged collectors(4-1) that have smaller venturi in them and are really ment for high power. Main factor about exhaust size is power(corresponds flow) and I think no D-series with 4-2-1 header is making so much power to require 2.5" exhaust without any venturis or something..

transzex

10-09-2006, 02:10 PM

being my collector is 1.875 on the Stillen, Dave@SMSP even said I need to go bigger.......might have been holding me back while spraying :)

SMSP

10-09-2006, 08:19 PM

2.5" exhaust seemed to help my 4-2-1.

http://honda-tech.com/zerothread?id=1739065

AMkrew_1

10-09-2006, 10:44 PM

being my collector is 1.875 on the Stillen, Dave@SMSP even said I need to go bigger.......might have been holding me back while spraying :)

Maybe, lol.

We ghetto'd a 2nd piece of a header to fit on a buddies crx that was spraying. We hacked off the collector, and welded(if you can call it that:sadface: ) a 2.5" pipe on there, all crooked and stuff. It was good for a couple mph on the spray compared to the stock chikara 2nd piece.
-josh-

turboedpickup

10-09-2006, 10:45 PM

2.5" exhaust...from the header - or after... and about the cat. would a 2.5" inlet/outlet cat be required? i guess my question is... if the header outlet is 2"...and my cat is stock size (dx eg) ...and my exhaust piping is 2.5" - the bottle neck's the cat? .....and are "bigger" pipe diameter cats CARB legal (in cali)?

20civic00

10-09-2006, 10:50 PM

fuck california's emmisions! just put the stock exhaust back on for the smog tests. thats what im doin. of course i had the cat relocated and its really not a "cat" just kinda a resonator with a bung hole. lol

AMkrew_1

10-09-2006, 10:54 PM

20civic00

10-09-2006, 10:56 PM

huh, huh... Heh, heh... You said "bung hole"... Huh, huh.
-josh-

yeah it is a goofy word. buuuung hole...problem is it doesnt roll off the tongue. lol